Mechanistic insights into levan elongation by levansucrase from phytobacteria Erwinia tasmaniensis for tailored levan biosynthesis
Issued Date
2026-02-01
Resource Type
ISSN
01448617
eISSN
18791344
Scopus ID
2-s2.0-105020931528
Pubmed ID
41320395
Journal Title
Carbohydrate Polymers
Volume
373
Rights Holder(s)
SCOPUS
Bibliographic Citation
Carbohydrate Polymers Vol.373 (2026)
Suggested Citation
Charoenwongpaiboon T., Benini S., Field R.A., Klaewkla M., Lorthongpanich C., Pongsawasdi P., Pichyangkura R., Wangpaiboon K. Mechanistic insights into levan elongation by levansucrase from phytobacteria Erwinia tasmaniensis for tailored levan biosynthesis. Carbohydrate Polymers Vol.373 (2026). doi:10.1016/j.carbpol.2025.124616 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/114571
Title
Mechanistic insights into levan elongation by levansucrase from phytobacteria Erwinia tasmaniensis for tailored levan biosynthesis
Corresponding Author(s)
Other Contributor(s)
Abstract
Levansucrase catalyzes the polymerization of fructose units from sucrose into a β-2,6-linked fructan called “Levan”, which are versatile in many applications. While levansucrases from Gram-positive bacteria have well-characterized levan-binding track, the molecular basis for levan elongation by Gram-negative bacteria enzymes remains unclear. Here, we integrated rational mutagenesis, biochemical assays, and molecular dynamics (MD) simulations to elucidate the levan-binding architecture of levansucrease from the Gram-negative bacteria Erwinia tasmaniensis ( Et Lsc). Using surface topology and residue-frequency mapping, we identified three potential carbohydrate-binding tracks. Alanine scanning of 19 residues revealed that mutations in a distinct surface loop (track II) significantly decreased levan production, particularly F376A, which also abolished gel retention in levan-affinity PAGE. MD simulations proposed strong interactions between levan oligosaccharide and residues F376 and F349, and highlighted a conformational change within the 368–378 loop upon substrate binding. Interestingly, mutations in a second region (track III) selectively altered the product spectrum of β-2,1 fructooligosaccharides and promote levan biosynthesis, suggesting a dual-track model for fructan synthesis. Taken together, the results reveal a unique elongation mechanism in Gram-negative bacteria levansucrases that diverges from that of enzymes from Gram-positive bacteria. These findings provide a structural framework for engineering levansucrases with tunable product profiles for carbohydrate biotechnology applications.